Exploring DIY control options for an AC unit not designed for home automation

Hardware
1

Hi everyone,

I’m looking into the possibility of adding some level of home automation to an air conditioner that wasn’t originally designed for it. After opening the unit, I found a control board labeled A010403 V1.3 KB-5150 CEM-1.

The board exposes two connectors that look promising:

  • RX / TX / GND / 5V
  • 5V / SCL / SDA / GND (likely I2C)

I’ve tried probing these interfaces with an Arduino (serial and I2C scanning), but haven’t been able to get any meaningful data so far. Before digging deeper, I wanted to check if anyone here has experience reverse-engineering AC control boards or adding Home Assistant compatibility to units that don’t support it natively.

I’ll attach a reference photo of the V1.2 board (mine is V1.3, but nearly identical).

A010403 V1.2
A010403 V1.2679×610 91.5 KB

Any insights, best practices, or experiences would be greatly appreciated.

2

Maybe is controling via IR also an option as an alternative.

1 Like
3

It is TCL CN16 protocol, in your picture is is near switch 1, there are some project out there like this: GitHub - xaxexa/ESPHome-TCLAC: wifi module for tcl-tac09chsa can control it. Or you can contact me, have design board can work with it

1 Like
4

Thanks a lot for the information. Knowing that it uses the TCL CN16 protocol really helps. I went through the GitHub project you shared, but I’m still not fully sure how the wiring should be done in practice.

I have several ESP32 boards available, so I could try to build the connections myself, but I’m not completely sure which pins should go to which lines on the CN16 header or whether level shifting or any protection is required.

If you have any guidance, a simple diagram, or just a quick explanation of the wiring, that would really help me move forward. Thanks again for pointing me in the right direction.

5

Thanks for the suggestion. That’s actually how I’m controlling it right now, using IR. It works, but the downside is that there’s no state feedback at all, which is a bit limiting. That’s why I’m exploring the direct control option.

6

It is very simple, On the main-board have 4 pin with 5V DC pin, GND pin and TX RX, you can using a level shifter wire esp32 with it, because esp32 have 3.3v logic level, the main board 5 volt. this 5VDC pin can power the esp32 too.

image
image737×367 4.73 KB